The most important question is, if the FDA adopts these warnings, will they be effective? A review (see study in Tobacco Control) of the existing scientific literature appears to suggest that yes, they will. And the more shocking, the better.

Here are some conclusions Canadian research David Hammond drew from his analysis of 94 original articles:

The impact of health warnings depends upon their size and design.

Obscure text-only warnings appear to have little impact.

Prominent health warnings on the face of packages serve as a source of health information for smokers and non-smokers.